CN211778831U - Homothetic differential speed reducer - Google Patents

Abstract

The homothetic differential speed reducer is a speed reducer with homothetic differential gear train, its transmission structure is designed by combining difference logic and multiple logic, the size of speed reducing ratio is inversely related to the size of difference value of two contrasted rotating speeds, and said difference value can be infinitely close to zero from positive and negative directions, so that the speed reducing ratio also can be moved toward infinity or infinity, and the speed reducing ratio can not mainly determine how large the multiple of geometric parameter between the components of the transmission wheel set can be, but mainly determines how close the multiple of geometric parameter of two transmission wheel sets can be, so that under the condition of identical size, it can obtain wider output range and larger speed reducing ratio, or under the same speed reducing ratio it has smaller volume or larger load-carrying capacity. On the basis, return difference is reduced by adopting various zero backlash transmission methods, and more excellent comprehensive performance and a larger application range are obtained by matching with other various technical methods.

Description

Homothetic differential speed reducer

Technical Field

The utility model relates to a reduction gear, especially with the reduction gear that comparatively extreme technical feature is relevant such as super large reduction ratio, zero backlash.

Background

The reducer, which is an indispensable transmission device in the field of power machinery, has evolved into a great number of structural types along with the development of industrial civilization in the world for hundreds of years, and is now developing at a high speed in the fields of aerospace, automation, robots and the like, and is also facing a new round of development opportunity, and meanwhile, the reducer also faces higher requirements in various aspects such as transmission ratio, return difference, precision, strength and the like. The prior coaxial speed reducer mainly comprises planets, pinwheel cycloid, rotation vector RV and harmonic wave, the transmission mode is tooth transmission, wherein, as the type with the widest application, the reduction ratio of the planetary speed reducer is determined by the multiple relation of the geometrical parameters such as the diameter, the tooth number and the like of a transmission pair component, the whole transmission structure is also designed according to multiple logic, the basic speed change principle forms the planetary speed reducer, but the basic speed change principle also forms an elbow braking factor which hinders the performance of the planetary speed reducer to be further improved, because of the limitation of material strength and correct meshing conditions, the geometrical parameters of a pinion of the transmission pair can easily reach the minimum limit, the diameter and the tooth number of a bull gear can be increased or the transmission stage number can be increased when a larger transmission ratio is obtained, so that the structure becomes more complex, the volume, the weight and the manufacturing cost are increased, more importantly, the side clearance is gradually increased to increase the return difference, therefore, the method is not suitable for being applied to the fields such as robots and the like which require small volume and high precision. The pin wheel cycloid speed reducer, rotation vector RV reduction gear and harmonic reduction gear have higher transmission precision, but what adopt is few tooth difference speed reduction principle, the size of drive ratio is determined by the tooth number difference and the gear wheel number of teeth, the tooth number difference is too little or the number of teeth of gear wheel is too few all produces the interference easily, also can face the gear wheel when needing big drive ratio big not big enough, the condition that the number of teeth difference is not little enough, for avoiding interfering, the gear often still need the type of repairing and make manufacturing and maintenance inconvenient, in addition, comparatively complicated for planetary reduction gear structure, weak, make load-carrying capacity restricted. Different technical types have advantages and disadvantages, and one type of speed reducer is difficult to simultaneously meet the requirements of multiple aspects.

SUMMERY OF THE UTILITY MODEL

The utility model aims at providing a reduction gear with apposition differential gear train combines difference logic and multiple logic to design transmission structure, makes the difference of the reduction ratio of two transmission wheelsets correlate with the output result of reduction gear to obtain the output range and the great reduction ratio of broad more easily, perhaps have less volume or great load-carrying capacity under same reduction ratio. On the basis, the backlash is reduced by adopting various methods for reducing the backlash, and other various technical methods are matched to obtain more excellent comprehensive performance and a larger application range.

The driving wheels of the utility model comprise a homothetic differential gear train which comprises a synchronous set and a differential set, wherein the synchronous set is a compound planet wheel or a flat wheel set, the differential set is two coaxial driving wheels, one is a stator, and the other is a rotor; the homothetic differential gear train uses the synchronous set as an input element and uses the rotor as an output element; the middle shaft is a power shaft, the connection mode between the synchronizing group and the middle shaft is that a rotating arm or an eccentric wheel is fixedly connected with the middle shaft, the composite planet wheel is rotatably arranged on the rotating arm or a flat rotating wheel group is rotatably connected with the eccentric wheel, or the middle shaft and the composite planet wheel or the flat rotating wheel are connected through a preceding stage speed reducing mechanism, or the middle shaft is a hollow shaft, and the composite planet wheel is directly rotatably arranged on the non-coaxial position of the middle shaft.

The utility model discloses a drive wheel of apposition differential gear train is the gear, adopts the mode of synchronous group grouping crack elimination to come the transmission, and synchronous group unit falls into two sets of directions work that only are in the difference respectively, and when a group worked, another group was in the operating position that is closer to another direction than this group, and concrete method includes "teeth of a cogwheel dislocation method", "surpasss from legal" and "reverse circumference power method".

The utility model discloses a homotopic differential gear train adopts current anti-backlash gear to carry out zero backlash transmission, perhaps adopts meshing direction pre-pressure mounting means to eliminate the backlash.

The utility model discloses a two drive wheel branches of differential group do not occupy each other's radial outside space in the different positions of axial, perhaps, do not have other subassembly to occupy the radial outside space of stator or rotor, therefore their transmission point can all arrange the position of comparatively keeping away from the center in overall structure to it is less to make the backlash return stroke angle.

The utility model discloses a drive wheel is at centraxonial axial drive, and two apposition wheels of synchronous group combine into the step pulley, and differential group is radially intussuscepted each other, and the rotor directly regards as slewing bearing with the stator, or separates the supporting arrangement who has motion drag reduction effect or bear the axial force effect.

The utility model discloses have axial position adjusting device and controlling means thereof, can be used for adjusting the drive wheel backlash size, perhaps balanced drive wheel axial force, perhaps adjust transmission frictional force, can manual or automatic control.

The utility model discloses have integrated power device, the input component of apposition differential gear train also is power device's output member simultaneously, perhaps, the stator direct mount of apposition differential gear train is on power device's fixed part, perhaps, apposition differential gear train and power device are in radial intussusception distribution.

The utility model discloses a homotopic differential gear train is including asymmetric gear, and its flank profile is about asymmetric shape, perhaps, and its left and right flank has different heat resistance, antifriction performance that wear-resistants, intensity or toughness.

The utility model discloses a mix in the same apposition differential gear train and use the gear of different modulus, make its driving wheel group and even whole apposition differential gear train have more abundant drive ratio to select under the same magnitude of dimension.

The driving wheel of the homothetic differential gear train of the utility model is a friction wheel or a magnetic wheel.

Positive effect

The reduction ratio of the homothetic differential gear train is inversely related to the difference between two contrast rotating speeds of the differential group, and the difference can be infinitely close to zero from positive and negative directions, so the reduction ratio of the homothetic differential gear train can also tend to be infinite or infinitesimal, the reduction ratio can not determine how large the times of the geometric parameters between the components of one transmission wheel group are but determine how close the times of the geometric parameters of the two transmission wheel groups are, the restriction degree of the size of the transmission wheel on the reduction ratio is weakened, a wider output range and a larger reduction ratio can be obtained under the condition of equivalent size, or smaller volume or larger load capacity can be obtained under the same reduction ratio. Taking a basic structure as an example, in a homothetic differential gear train formed by two transmission gear sets of a 109-tooth pair 37 teeth with a modulus of 0.5 and a 91-tooth pair 31 teeth with a modulus of 0.6, the 37 teeth and the 31 teeth are synchronous sets, and the 109 teeth and the 91 teeth are differential sets; the synchronous group is used as an input element to drive the differential group in a driving revolution mode, 91 teeth are fixed, and 109 teeth are used as output elements; the synchronous group rotates for 2.94 circles in each 1 revolution, the angular displacement difference of 91 teeth and 109 teeth is only 0.0012 circles in each 1 revolution, and the total speed reduction ratio of the whole gear train is 283: 1, a larger reduction ratio is obtained under the condition of less teeth, and the limit is far not reached, which is difficult to be achieved by other reducers under a single-stage reduction structure; in conventional applications, the reduction ratio is generally less than 100, the transmission wheels require fewer teeth, the same module can be maintained to make the gear volume smaller, and a larger module can be used to make the gear teeth larger to improve the load capacity. The homothetic differential gear train has at least four driving wheels of two driving wheel sets to participate in transmission, the number of the driving wheels is more, but the transmission ratio range is greatly expanded, because the number of the driving wheels is more, the variables influencing the output result are more, and the selectable output result is richer due to the application of different moduli, so the application range is wider. In general, the longer the transmission chain, the worse the precision, but because two transmission wheel sets of the homodromous differential gear train are in homodromous relationship, the total amount of the radial clearance of the gear in the whole size and the difficulty of precision control are not increased, in some embodiments, such as a structure that a synchronous set and a rotor move in the same direction, the gear backlash influencing the backlash size is only from the transmission wheel set with the larger backlash, and the backlash link of one transmission wheel set can be only one, when a transmission point is arranged at a position with a larger diameter on the basis of the shortest transmission chain or a zero backlash transmission mode is combined, and the high rigidity characteristic of the gear transmission is combined, the backlash can be controlled in a small range, which is an important characteristic that an excellent speed reducer should have. The transmission wheel of the homothetic differential gear train can achieve the performances of large reduction ratio, zero backlash and the like only by a standard involute gear, the system has the advantages of reliable transmission, strong impact resistance, balanced stress, long service life, low manufacturing cost and the like, and when the embodiment of the friction wheel or the magnetic wheel is adopted, the structure is simpler, and the system is valuable in application occasions of low precision, low load, maintenance-free, flexible silence, miniature light weight, overload protection and the like. When the homothetic differential gear train adopts a transmission structure with intersecting shafts or staggered shafts, the backlash can be adjusted through the displacement between the meshing pairs in the axial direction or the offset direction, the differential groups can be radially overlapped to save space, and the distribution radius of the synchronous groups can be smaller than that in a parallel shaft structure, so that the radial size and the motion inertia are smaller. In the zero backlash transmission embodiment, one of the left tooth surface and the right tooth surface is a working surface, and the other is a non-working surface, and the asymmetrical tooth profile shape and different materials, processing methods or processing precisions are adopted in a targeted manner to enable the tooth surfaces to have different mechanism structures, roughness or physical properties, so that different tooth surfaces can meet different requirements or save cost. The reduction transmission system is integrated with the power device, so that the whole structure is more compact, and the reduction transmission system is beneficial to simplifying the structure, reducing the volume and lowering the cost.

Drawings

FIG. 1 is an embodiment in which the synchronizing group is a planetary gear set;

FIG. 2 is an embodiment in which the synchronization group is a sun gear;

FIG. 3 is an embodiment in which the synchronization group is a level wheel;

FIG. 4 is a plan view of a two-stage reduction embodiment of the rotatable wheels;

FIG. 5 is a planetary secondary reduction embodiment;

FIG. 6 is a hollow shaft embodiment;

FIG. 7 illustrates a first method for eliminating backlash of synchronization packets;

FIG. 8 is a second synchronization group packet anti-backlash method;

FIG. 9 illustrates a third method for anti-backlash of the sync group;

FIG. 10 is a radially nested embodiment of bevel gears;

fig. 11 shows an integrated embodiment of the reduction mechanism and the power unit.

Detailed Description

The driving wheel of the utility model comprises a homothetic differential gear train which comprises a synchronous group and a differential group, wherein the synchronous group is a compound planet wheel or a flat wheel group, the differential group is two coaxial outer rings, one is a stator, and the other is a rotor; the homothetic differential gear train uses the synchronous set as an input element and uses the rotor as an output element; the middle shaft is a power shaft, a rotating arm or an eccentric wheel is fixedly connected with the middle shaft, the composite planet wheel is rotatably arranged on the rotating arm or the flat rotating wheel group is rotatably connected with the eccentric wheel, or the middle shaft is connected with the composite planet wheel or the composite flat rotating wheel through a preceding stage speed reducing mechanism, or the middle shaft is a hollow shaft, and the composite planet wheel is directly rotatably arranged on the middle shaft. The homothetic transmission wheel set refers to two transmission wheel sets, wherein the transmission wheel of one transmission wheel set and the transmission wheel of the other transmission wheel set correspond to each other in mounting direction or transmission relationship, a common rotating shaft or a rotating shaft which is parallel to each other is arranged, at least one of the transmission wheels in the respective sets is in the same transmission direction, for example, both the transmission wheels are sun wheels, planet wheels or outer rings, or the transmission objects are sun wheels, planet wheels or outer rings; the transmission wheels corresponding to each other are the same-position wheels, the corresponding mode of the same-position wheels can be that the driving wheels correspond to the driving wheels and the driven wheels correspond to the driven wheels, or the driving wheels and the driven wheels correspond to each other in a crossed manner. The utility model discloses an among the apposition driving wheelset, there is a set of apposition wheel simultaneous movement, also known as synchronizing wheel, their combination is synchronous group, revolution, rotation or revolution and rotation simultaneously with the same or opposite angular velocity each other, the concrete form of combination includes but not limited to step wheel, coaxial wheel, the asynchronous movement of two other apposition wheels, it is called the differential wheel, one of them can rotate, it is called the rotor, another fixed mounting is as the reference system, it is called the stator, their combination is differential group. Referring to fig. 1, a middle shaft 6 is rotatably connected with a base 12 through a shaft sleeve 13, a rotating arm 5 is fixedly connected with the middle shaft 6 and is rotatably connected with a rotating shaft 4 through a bearing 3, a first planet wheel 2 and a second planet wheel 10 are fixedly connected with the rotating shaft 4 to form a synchronous set which can synchronously rotate and revolve, and more than two synchronous sets are uniformly distributed in the circumferential direction; the second outer ring 9 is fixedly arranged on the base 12, the first outer ring 1 takes a bearing 8 fixed on the end face of the second outer ring 9 as a rotary support, and the first outer ring 1 can only take the first planet wheel 2 as a floating support; the first outer ring 1 and the second outer ring 9 form a differential group by taking the central shaft 6 as a common shaft center, and are respectively transmitted with the first planet wheel 2 and the second planet wheel 10 to form two homothetic transmission wheel groups, namely a homothetic differential gear train with a basic structure. When power is input from the middle shaft 6 to drive the synchronous set to revolve, the rotating speed of the first outer ring 1 with the second outer ring 9 as a reference is positively correlated with the difference of the transmission ratios of the two homothetic transmission wheel sets, the transmission ratio of the whole homothetic differential gear train is negatively correlated with the rotating speed of the first outer ring 1 with the second outer ring 9 as a reference, the difference of the transmission ratios of the two transmission wheel sets is smaller, the value of the transmission ratio of the whole homothetic differential gear train is larger, and when the difference of the transmission ratios of the two transmission wheel sets is zero, the transmission ratio is infinite or infinitesimal. The homothetic differential gear train performs speed reduction transmission by using the first outer ring 1 as an output element, or performs acceleration transmission by using the first outer ring 1 as an input element, and different transmission ratios can be obtained by changing the difference of the transmission ratios of the two transmission wheel sets. In order to balance the forces on the bearing 3, a sun wheel, which is movably connected to the central shaft 6, may be provided to balance the radial forces on the first planet wheels 2 and the planet wheels 9. The types of drive wheels that can be used in the co-located differential gear train include, but are not limited to, gears, sprockets, pulleys, flexspline, friction wheel, magnetic wheel, and other closed-turn flexures that function in a configuration including, but not limited to, an inner ring, an outer ring, a sun wheel, a planet wheel, a roller wheel, a flat wheel, and a vector of rotation RV wheel. When the drive wheels are gears, of the type including but not limited to spur, helical, bevel or face gears, and of the type including but not limited to involute, circular arc, cycloid or parabola, different sets of drive wheels preferably have the same modulus, but may have different moduli to achieve a more suitable drive ratio. In the embodiment of fig. 1, the synchronizing wheel and the differential wheel are directly driven, or an intermediate wheel may be provided for driving, as in the embodiment shown in fig. 2, the first sun wheel 20 and the second sun wheel 21 are fixedly connected with the middle shaft 22 to form a synchronizing group, and the intermediate wheel group formed by fixedly connecting the first intermediate wheel 17 and the second intermediate wheel 18 drives the first outer ring 15 and the first outer ring 16 of the differential group. Fig. 3 shows an embodiment in which the synchronizing group is a flat wheel group-the first flat wheel 26 and the second flat wheel 32 are rotatably connected by a plurality of small cranks 27 and rotatably connected to the central shaft 29 by means of a sleeve 28 and an eccentric 30, thus forming a synchronizing group capable of eccentric flat rotation, which is in transmission with the outer ring 25 and the outer ring 31 of the differential group, respectively. The coordinated differential gear train can also be provided with a speed change device to form a two-stage speed change structure, wherein, as shown in the embodiment of fig. 4, the first outer ring 35 and the second outer ring 39 are a differential group, the first flat rotating wheel 36 and the second flat rotating wheel 41 are a synchronous group, the small crank 37 rotationally connected with the first flat rotating wheel 36 and the second flat rotating wheel 41 is connected with the central shaft 38 through speed reducing wheels 40 and 42, as shown in the embodiment of fig. 5, the first outer ring 43 and the second outer ring 49 are a differential group, and the first planet wheel 44 and the second planet wheel 50 form a synchronous group and are connected with the central shaft 47 through speed reducing wheel groups 45 and 48. In the embodiment of fig. 6, which is still another way of connecting the synchronizing group to the power, the first planetary gear 52 and the second planetary gear 55 are fixedly connected to the rotating shaft 53 to form the synchronizing group, and are respectively in transmission with the first outer ring 51 and the second outer ring 54 of the differential group, the rotating shaft is rotatably mounted on the hollow shaft 56, and the hollow shaft 56 is driven by the power device or is an output element of the power device, and can drive the synchronizing group to revolve. In the case of multiple output results, the homothetic differential gear train may be of composite structure with multiple transmission wheel sets, synchronous sets, differential sets, stators or rotors, and different working combinations may be selected by switching the output gears.

Referring to fig. 7, the co-located differential gear train is driven by adopting a synchronous group backlash eliminating mode — a first outer ring 57 and a second outer ring 58 depicted by a dotted line are differential groups, the first outer ring 57 is a stator, the second outer ring 58 is a rotor, the first outer ring and the second outer ring take a point O as a center, and a first planet wheel 59 and a second planet wheel 60 depicted by a solid line form a compound planet wheel as a synchronous group; the first planetary wheel 59 drives the first outer ring 57, the second planetary wheel 60 drives the second outer ring 58, the rotation direction of the second outer ring 58 is opposite to the revolution direction of the compound planetary wheel by selecting the magnitude relation of the transmission ratio of the two transmission wheel sets, the working surfaces of the first outer ring 57 and the second outer ring 58 face oppositely at the same time, and the working surfaces of the two transmission wheels of the same compound planetary wheel unit also face oppositely; more than two composite planet wheel units are divided into two groups, for the purpose of stress balance, the number of the composite planet wheel units in each group is preferably even, and the composite planet wheel units are uniformly distributed in the same group in the circumferential direction or uniformly mixed; the relative angles of the two driving wheels of the compound planetary wheel units of different groups are different, so that the first planetary wheel 59 of one group works only in the clockwise direction, the second planetary wheel 60 works only in the anticlockwise direction, the first planetary wheel 59 of the other group works only in the anticlockwise direction, the second planetary wheel 60 works only in the clockwise direction, when one group works, the other group is in a working position which is closer to the other direction than the group, and the other group is in non-contact or non-pressure contact with the working tooth surface of the differential group, or the non-working tooth surface of the differential group can be in non-load contact or a small backlash which does not influence normal transmission can be reserved, so that zero backlash transmission can be realized by using a common gear, and the method is 'gear tooth dislocation method'. Zero backlash in the drive means that there is not absolutely no backlash, but that the backlash approaches the minimum backlash under ideal conditions when the drive is running normally. The synchronous grouping backlash can also be realized by an overrunning clutch method shown in fig. 8, wherein fig. 8 is added with an overrunning clutch 85, a magnetic ring 86 and a planet carrier 87 on the basis of fig. 5; by selecting the magnitude relation of the transmission ratios of the two transmission wheel sets, the rotation direction of the first outer ring 43 is the same as the revolution direction of the compound planet wheel, the working surfaces of the first outer ring 43 and the second outer ring 49 face the same at the same time, and the working surfaces of the two transmission wheels of the same compound planet wheel unit face the same; the rotating shaft of each compound planet wheel is rotationally connected with the planet carrier 87 and is provided with an overrunning clutch 85, the magnetic ring 87 is fixed on the ring 47, and the outer ring of the overrunning clutch 85 is a magnetic ring which can be driven by the magnetic force action with the magnetic ring 86; a plurality of composite planet wheel units are divided into two groups A and B, more than two groups are suitable for each group, and the installation directions of the overrunning clutches 85 of the two groups are opposite; the transmission ratio of the first transmission wheel 48 to the second transmission wheel 45 is greater than the transmission ratio of the overrunning clutch 85 to the magnetic ring 86, when the middle shaft 47 drives the first driving wheel 48 to rotate in one direction, the overrunning clutch 85 of the group A is in a separated state, the state of the compound planetary gear unit is not affected, and the overrunning clutch 85 of the group B is in a combined state, so that the compound planetary gear unit connected with the overrunning clutch is away from the working position at a rotating speed which is faster than the working rotating speed, finally reaches the working position in the other direction and keeps a ready state, at this time, the magnetic force between the outer ring of the overrunning clutch 85 and the magnetic ring 86 is far smaller than the rigid resistance between the transmission wheel sets to mutually slip and rotate, when the middle shaft 47 drives the first transmission wheel 48 to rotate reversely, the group B works and the group A is in a ready state, so that the backlash between the first transmission wheel 48 and the second transmission wheel 45 is eliminated; the positions of the magnetic ring 86 and the overrunning clutch 85 can be interchanged, and the outer rings of the magnetic ring 86 and the overrunning clutch 85 can be replaced by friction rings; the backlash between the sync and differential sets of the embodiment of fig. 1 can be eliminated by the same principle. The 'reverse circumferential force method' can also be adopted, as shown in fig. 9, the compound planetary wheel units 88 of the same group are arranged in pairs and opposite to each other, and are meshed with the gears 89 at the two ends of the reed 90, the gears 89 are tightened towards the center under the action of the reed 90, and the compound planetary wheel units 88 of different groups are respectively applied with reverse circumferential forces to be located at working positions in different directions. The specific method of implementing packet anti-slot is not limited to the above list.

In addition to the synchronous grouping anti-backlash mode, the homothetic differential gear train can also adopt the existing anti-backlash gears to perform zero backlash transmission, and the homothetic differential gear train comprises but is not limited to non-standard tooth profile gears, layered staggered gears and axial staggered herringbone gears. The gear teeth of the gear with the non-standard tooth profile can be transmitted with zero backlash after being specially modified and ground; the layered staggered gear is a cylindrical straight gear, a cylindrical helical gear or a bevel gear, and is axially divided into two thin-plate gears which are mutually staggered in the circumferential direction by a small angle, the bevel gear can also be radially layered, and the layered staggered gear is matched with a non-layered gear to reduce the backlash on the whole tooth width; the axial dislocation herringbone gear refers to that two correctly meshed herringbone helical gears are displaced in the axial direction, so that one section of two sections of the herringbone gear teeth is withdrawn from the working position, and the backlash on the whole tooth width is reduced. In addition, an installation mode of applying pre-pressure in the meshing direction can be adopted, no side gap is left during installation, and the device is particularly suitable for a cycloidal gear and a pin wheel meshing pair.

Referring to fig. 1, the first outer ring 1 and the second outer ring 9 of the differential set are at different positions in the axial direction, do not occupy the radial outer space of each other, the connection position between the first outer ring 1 and the second outer ring 9 is in the end face direction, and no housing or other components occupy the radial outer space of the first outer ring 1 or the second outer ring 9, so that the transmission points can be arranged at positions far from the center in the whole structure, and the backlash return angle is small.

As in the embodiment of fig. 10, the driving wheel is a bevel gear, a face gear or a helical gear which drives in the axial direction, and may also be a friction wheel or a magnetic wheel, and the differential group is composed of an outer ring 67 and an inner ring 69, one of which is a stator and the other of which is a rotor; the synchronous group is formed by fixedly connecting a first driving wheel 61 and a second driving wheel 63; the rotating shaft 62 is rotatably connected with a connecting block 64 fixed on a middle shaft 65, and the middle shaft 65 is rotatably connected with an inner ring 69; the outer ring 67 and the inner ring 69 may be supported axially via a sleeve 68, and one of the rotors may be directly used as a slewing bearing or one of the stators may be used as a slewing bearing, or the sleeve 68 may be a composite structure. This radially nested configuration saves axial space and for other design purposes can also be arranged opposite each other on both axial sides of the synchronization group.

Referring to fig. 10, the threaded sleeve 66 can move axially along the external thread of the central shaft 65 when rotating in different directions, and can be used to adjust the backlash of the gears, or to balance the axial force of the driving wheel, or to adjust the friction force of the driving wheel. The threaded sleeve 66 is also connected with a locking device, a manual control device or an automatic control device. The threaded sleeve 66 is a position adjusting device, and the technical type thereof and the control device matched with the threaded sleeve are not limited to a threaded structure, and the technical types thereof can be adopted by the position adjusting device and the control device matched with the position adjusting device include but not limited to mechanical devices such as a lever, a pull rope, an eccentric wheel, a wedge block and the like, and liquid, gas, sound, light, magnetism, electricity, heat or the combination of the above various types.

To improve integration, the parity differential gear train may be integrated with an electric motor, an engine or other type of power plant, the input component of the parity differential gear train being also the output component of the power plant, as in the embodiment of fig. 6, or the stator of the parity differential gear train being mounted directly on a stationary component of the power plant, such as the housing, or the parity differential gear train and the power plant being nested radially. As in the embodiment of fig. 11, the differential group is composed of a first outer ring 70 and a second outer ring 78, the synchronous group is composed of a first planetary gear 72 and a second planetary gear 80 which are fixedly connected through a rotating shaft 73, the rotating shaft 73 is rotatably connected with a rotating arm 75 fixed on an outer rotor 76 of the motor through a bearing 71, and a stator 77 of the motor and the second outer ring 78 of the differential group are both fixed on a base 81.

When a synchronous component group backlash eliminating structure is adopted or layered staggered gears and axial staggered herringbone gears are adopted for transmission, the same gear tooth of some transmission wheels only bears load in one direction, a pressure bearing face needs to have higher hardness and better heat resistance, wear resistance and friction reduction performance, a non-pressure bearing face needs to have higher compressive strength and toughness, and in order to enable different gear faces to respectively meet different requirements, an asymmetric tooth profile shape can be adopted, for example, a working face is taken as a standard parameter, a non-working face is thickened in the circumferential direction and provided with oil grooves, or different surface materials or processing methods are respectively adopted, so that the non-pressure bearing face and the non-pressure bearing face have different mechanism structures, roughness or physical properties.

The gears with different modules are mixed in the same homothetic differential gear train, and different transmission wheel sets adopt different modules, so that the transmission wheel sets and even the whole homothetic differential gear train have richer transmission ratio selection under the same magnitude size.

The transmission wheel of the homothetic differential gear train is a friction wheel or a magnetic wheel.

Claims (10)

1. The homothetic differential speed reducer comprises an input element, an output element and a transmission wheel, is directly arranged on other objects or is also provided with a base or a middle shaft, and is characterized in that the transmission wheel comprises a homothetic differential gear train which comprises a synchronous set and a differential set, wherein the synchronous set is a compound planet gear or a flat pulley set, the differential set is two coaxial transmission wheels, one is a stator, and the other is a rotor; the homothetic differential gear train uses the synchronous set as an input element and uses the rotor as an output element; the middle shaft is a power shaft, the connection mode between the synchronizing group and the middle shaft is that a rotating arm or an eccentric wheel is fixedly connected with the middle shaft, the composite planet wheel is rotatably arranged on the rotating arm or a flat rotating wheel group is rotatably connected with the eccentric wheel, or the middle shaft and the composite planet wheel or the flat rotating wheel are connected through a preceding stage speed reducing mechanism, or the middle shaft is a hollow shaft, and the composite planet wheel is directly rotatably arranged on the non-coaxial position of the middle shaft.

2. The homothetic differential speed reducer according to claim 1, wherein the transmission wheels of the homothetic differential gear train are gears, and the transmission is performed by a synchronous group backlash eliminating method, the synchronous group units are divided into two groups, and the two groups respectively operate only in different directions, and when one group operates, the other group is located at an operating position closer to the other direction than the one group, and the specific method includes a "gear tooth dislocation method", an "overrunning separation method" and a "reverse circumferential force method".

3. The reduction gear according to claim 1, wherein the homothetic differential gear train uses an existing anti-backlash gear to perform zero backlash transmission or uses an engagement direction pre-pressure installation mode to eliminate backlash.

4. A co-located differential reducer according to claim 1, 2 or 3, in which the two drive wheel sections of the differential set are at axially different positions, occupying no radially outer space from each other, or no other component occupies no radially outer space of the stator or rotor, so that their drive points can be arranged at positions relatively far from the center in the overall structure, thus making the backlash return angle small.

5. A speed reducer according to claim 1, 2 or 3, characterized in that the drive wheels drive axially on the central shaft, the two co-located wheels of the synchronizing group are combined into a step wheel, the differential group is nested radially one inside the other, the rotor is directly supported by the stator as a rotary support, or via a support device having a motion-damping effect or bearing an axial force.

6. A reduction gear according to claim 5, wherein the said axial position adjustment means and its control means are provided to adjust the backlash of the drive wheels, to balance the axial force of the drive wheels, or to adjust the friction of the drive wheels, either manually or automatically.

7. A reduction gear unit according to claim 1, 2, 3 or 6, characterized by an integrated power unit, wherein the input member of the parity differential gear train is also the output member of the power unit, or wherein the stator of the parity differential gear train is mounted directly on a stationary member of the power unit, or wherein the parity differential gear train and the power unit are radially nested.

8. The homothetic differential speed reducer according to claim 7, wherein the homothetic differential gear train includes an asymmetrical gear whose tooth profile is left-right asymmetrical or whose left and right tooth surfaces have different heat resistance, wear resistance, friction reduction properties, strength or toughness.

9. A reduction gear according to claim 1, 2, 3, 6 or 8, wherein gears of different modules are used in the same homothetic differential gear train, so that the transmission gear train and even the whole homothetic differential gear train have more abundant transmission ratio choices at the same order of magnitude.

10. The reduction gear unit according to claim 1, wherein the transmission wheels of the differential gear unit are friction wheels or magnetic wheels.

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